Machine for scraping tyres with controllable relative positioning of tyre and work tool

Abstract: A machine for scraping tyres and the like comprising means of handling (6, 106) and actuation (4, 104) of a tyre (7) made integral with a frame (1) according to a horizontal axis, constituting the axis of rotation of tyre (7) and of a work tool (11), and a device (8) for lifting the tyre, one (6) of such means of handling being capable of being operated in rotation but fixed in translation to constitute a fixed zero setting for positioning vertical axis of symmetry (z-z) of tyre (7), work tool (11) being capable of moving in a horizontal direction parallel to the axis of rotation of the tyre so as to achieve the positioning of their vertical axis of symmetry (y-y) in superposition with axis of symmetry (x-x) of the said tyre in relation to width dimension (x) of tyre (7) and to fixed reference (6).

Description: The object of this invention is a machine for scraping tyres and the like with the relative positioning of the tyre and the work tool being capable of being controlled in relation to a fixed reference. It is known that in the technology of the so-called retreading of tyres - that is, the replacement of the old, worn tread with a new tread - it is necessary to perform a preliminary operation to smooth the surface of the said tyre before applying the new tread. From JP-A-58001546 there is also known a machine in accordance with the preamble of claim 1, capable of performing this operation, commonly known as "scraping", in which provision is made for applying the tyre to be processed to a support consisting of two plates driven by mechanical arms the spacing of which corresponds to the thickness of the tyre being processed, according to the original geometrical features. Such machines are usually equipped with devices for centring the tyre with respect to an axis of symmetry which also represents the axis of symmetry of the work tool, which is fixed and represents in substance the reference setting for positioning the tyre. In such machines, however, it may happen that positioning of the tyre carcass in a central position does not prove correct because centring is obtained by means of pneumatic actuators the stroke of which is determined by the contact with the opposite faces of the tyre, which may not be correctly positioned, thus resulting in imperfect processing. There is therefore posed the technical problem of providing an automatic machine for scraping tyre carcasses which will make it possible to achieve centring of the work tool in relation to the axis of symmetry irrespective of the initial setting of the tyre in the work zone and in relation to the machine's own absolute, fixed and predetermined reference. Such results are obtained with the present invention, which provides a machine for scraping tyres and the like comprising means for handling and actuating of a tyre, which are integral with a frame according to a horizontal axis constituting the axis of rotation of the tyre and of a work tool, one of such means of handling may be driven in rotation but is fixed in translation to constitute a fixed zero reference for positioning the vertical axis of symmetry (z-z) of the tyre, while the other one of such means of handling is idle in rotation but capable of translation according to the horizontal axis of rotation of the tyre in order to bring about clamping thereof to enable the work tool to move in a horizontal direction parallel to the axis of rotation of the tyre so as to achieve the positioning of their vertical axis of symmetry (y-y) in superposition with the axis of symmetry (x-x) of the said tyre in relation to width dimension (x) of the tyre and to the fixed reference, there being also provided means of actuation of the means of handling and of the worktool, a device for lifting the tyre; means for actuation of the device for lifting the tyre, means for reading the measurement of movement of the means of handling, of the device for lifting the tyre and of the work tool, and a system for the control and actuation of positioning and of the phases of processing. Preferred embodiments are disclosed in claims 2-8. Further details may be obtained from the following description, with reference to the attached drawings, which show: In figure 1 : a schematic cross-section of the machine according to the invention, during the loading phase; In figure 2 : the machine in figure 1 during the processing phase, and In figure 3 : a schematic view of the operations performed by the work tool. As shown in the figures, the machine according to the invention is provided with a frame 1 to which are made integral two shoulders 1a and 1b. To shoulder 1a is attached a fixed tube 2 in which is inserted a shaft 3 capable of bringing about the rotation of a mandrel 4 upon operation of a motor 5 integral with shoulder 1a via a support 5a. To the free end of shaft 4 is applied in a known manner a plate 6 engaging tyre 7, which is held in position by means of an arm 8a of a lifting device 8 driven by a motor 8b. On opposite shoulder 1b is mounted like mandrel 104 to which is applied a plate 106 engaging tyre 7; such mandrel 104 rotates on bearings 104a keyed to a shaft 9 which is able to move horizontally driven by a motor 9a and with measurement of movement controlled by a reader 9b. In order to maintain a rectilinear stroke such shaft 9 is integral with a plate 10 connected to further guide shafts 10a and 10b. In the rear position relative to the front loading side of the machine is located the work tool, which is self-evident and therefore only shown schematically at 11. Such work tool is mounted on a support 12 driven by a motor 12a which brings about movement in a horizontal direction of the said tool, measurement of the movement of the tool being effected by means of a further optical reader 12b which ensures correct positioning of the axis of symmetry of the work tool to the axis of symmetry of the tyre, as will become clear from the following. Tool 11 is also made to rotate by appropriate means 11a around a horizontal axis orthogonal to the axis of rotation of the tyre, in order to enable the tangential contact of scraper 11 to be maintained on the tyre tread during processing, which is self-evident and therefore not described in detail. The machine is completed by a digital controller 50 which carries out all the operations of checking and comparison and sends a reference signal to the motors of the moving parts. The operation of the machine is as follows: tyre 7 is identified on the basis of its dimensions, with particular reference to width "X" of the zone corresponding to bead 7a, and is conveyed by lifting device 8 to a position substantially coaxial with that of mandrels 4, 104 and therefore of relevant handling plates 6, 106. At this point, horizontally moving mandrel 104 is made to advance toward fixed mandrel 4 so that the distance from moving plate 106 to fixed plate 6 - which represents the fixed point of absolute zero of the system of coordinates of the machine - does not coincide with measurement "X" of the width of the tyre, which thus engages facing plates 6, 106 by means of which it is made to rotate. Simultaneously, measurement "X" corresponding to the width of bead 7a of tyre 7 is sent to the controller of scraper 11, which is made to move by its own drive 12a by a quantity X/2 in order to cause its axis of symmetry Y-Y to coincide with axis of symmetry Z-Z of the tyre. At this moment the actual scraping operation commences. As can be seen, the machine according to the invention makes it possible to obtain in an automatic and reliable manner the correct positioning of the scraper with respect to the tyre being processed, in keeping with the true measurement of the said tyre and with reference to a fixed absolute zero, thus making it possible to avoid positioning errors. Many variants may be introduced without thereby departing from the scope of the invention in regard to its general features.

Claims: A machine for scraping tyres and the like, comprising means for handling (6, 106) and actuation (4, 104) of a tyre (7) made integral with a frame (1) according to a horizontal axis constituting the axis of rotation of tyre (7) and a work tool (11 ), one (6) of such means of handling being capable of being operated in rotation but fixed in translation to constitute a fixed zero reference for positioning the vertical axis of symmetry (z-z) of tyre (7), the other one (106) of such means of handling being idle in rotation but capable of translating according to the horizontal axis of rotation of tyre (7) in order to bring about clamping thereof to enable the worktool (11) to move in a horizontal direction parallel to the axis of rotation of the tyre so as to achieve the positioning of its vertical axis of symmetry (y-y) in superposition with said vertical axis of symmetry (z-z) of said tyre in relation to width dimension (x) of tyre (7) and said fixed reference, there being also provided means (5, 9a, 12a) for actuation of the means (106) of handling and of the worktool (11) characterised in that it comprises a device (8) for lifting the tyre, means (8b) for actuation of the device (8) for lifting the tyre, means (8c, 9b, 12b) for reading the measurement of movement of the means (106) of handling, of device (8) for lifting the tyre and of worktool (11), and a system (50) for the actuation of positioning and control of the phases of processing. A scraping machine according to claim 1, characterized in that such means of handling (6, 106) are comprised of plates (6, 106) respectively integral with such means of actuation (4, 104). A scraping machine according to claim 1, characterized in that such means of actuation in rotation of tyre (7) are substantially comprised of a pair of mandrels (4, 104) respectively mounted on a tube (2) secured to frame (1) of the machine and on a shaft (9) capable of moving horizontally. A scraping machine according to claim 1, characterized in that such fixed plate (6) constitutes the zero setting for the positioning of tyre (7) and of the work tools (11). A scraping machine according to claim 1, characterized in that such width of the tyre is width (X) corresponding to the position of bead (7a) of the said tyre. A scraping machine according to claim 1, characterized in that such means (8c, 9b, 12b) for reading the measurement of movement are optical readers. A scraping machine according to claim 1, characterized in that such control device is a digital controller (50). A scraping machine according to claim 1, characterized in that such work tools may rotate around two horizontal axes parallel to one another so as to maintain the tangency between the surfaces in contact with the tool and with the tyre being processed.

Inventors: MARANGONI GIORGIO, MARANGONI, GIORGIO
Applicants: MARANGONI MECCANICA, MARANGONI MECCANICA S.P.A.
Application year: 1994
Main classification: B29D30
IPC codes: B24B5, B24B49, B29D30